1. Field of the Invention
The present invention relates to a technique of controlling an operation of an electronic apparatus operable using, for example, a direct methanol fuel cell as a power supply.
2. Description of the Related Art
Recently, portable electronic apparatuses of various types such as a digital camera and a portable information terminal called a PDA (personal digital assistant) have been developed and widely used. Such electronic apparatuses are capable of being driven by a battery.
Moreover, recently, the issue of environment has received great attention and the development of environmentally-friendly batteries has been increased. A direct methanol fuel cell (hereinafter referred to as DMFC) is well known as such a battery.
The DMFC generates electric energy by chemical reaction between oxygen and methanol provided as fuel. The DMFC has a structure in which an electrolyte is interposed between two electrodes made of porous metal or carbon. Since the DMFC produces no hazardous wastes, its practicality is strongly desired.
In using the DMFC, it needs to be kept in a fixed direction without being tilted in order to prevent drawbacks of leakage of liquid fuel, load to various pumps due to the leakage, heat generation, etc.
For example, Jpn. Pat. Appln. KOKAI Publication No. 2002-063920 discloses a technique of preventing drawbacks from occurring when a fuel cell unit tilts. According to this technique, in order to prevent water from flowing backward to a fuel cell from a water tank even when the unit tilts, tubes are connected between outlets of the fuel cell and inlets of the water tank with their sleeves tucked up.
However, the above technique produces only the advantage of preventing water from flowing backward from the water tank and cannot overcome the other drawbacks due to a tilt of the fuel cell unit. Moreover, the internal structure of the fuel cell unit becomes complicated and accordingly the unit increases in size in its entirety.
In order to prevent the drawbacks due to a leakage of liquid fuel, it is considered effective that a tilt sensor should sense a tilt of the fuel cell unit.
However, only the sensing of a tilt of the unit by the tilt sensor cannot be regarded as measures enough to reliably avoid dangerous conditions. There is a possibility that the tilt sensor will be troubled for some reason.